Catalytic converter

ABSTRACT

A catalytic converter having an outer cylindrical housing and an inner cylindrical element adapted to receive in spaced relationship thereto a flat cylindrical catalyst element and having three distinct manifold portions: an annular portion between the housing and the element, an inner portion above the catalyst element and a lower portion below and surrounding the catalyst element. The annular portion communicates with the inner portion through a plurality of holes in the inner element and the inner portion communicates with the lower portion through the catalyst element whereby exhaust gases entering the annular portion are distributed around and radially into the inner portion and then flow uniformly downwardly through the catalyst element and into the lower portion to be discharged from the converter.

United States Patent Inventors Lester E. Patterson [56] References CitedGrand Blanc; I UNITED STATES PATENTS William L. Alley, Flushing; MichaeR. 054 664 9 1962 P 23 288 F FosterDavisonallof Mich. 3, 4 urse Appl.No. 38,771 Primary Examiner- Douglas Hart Filed May 19, 1970Att0rneys-Sidney Carter and Peter P. Kozak Patented Oct. 26, 1971 lMotCor oration Asslgnee Gene]?! 01.5 p ABSTRACT: A catalytic converterhaving an outer cylindrical Detroit, Mich.

houslng and an inner cylindrical element adapted to recelve in spacedrelationship thereto a fiat cylindrical catalyst element and havingthree distinct manifold portions: an annular portion between the housingand the element, an inner portion above the catalyst element and a lowerportion below and surrounding the catalyst element The annular portioncommu- CATLYTIC CQNVERTER nicates with the inner portion through aplurality of holes in 3clmmsznrawmg Figs the inner element and the innerportion communicates with [1.8. Cl. 23/288 F, the lower portion throughthe catalyst element whereby ex- 60/29 haust gases entering the annularportion are distributed Int. Cl. F0ln 3/14 around and radially into theinner portion and then flow Field of Search 60/29, 30; uniformlydownwardly through the catalyst element and into 23/288 F the lowerportion to be discharged from the converter.

:N J? I 7 if t {J 2y {i M W a4? M l ,//D a /5 73 y; s :4 r, i g

73? v 1Q 1 @QQYW. Q Q

f 4 40* if; I Tr 4:4; t a 1 f t f I 1 7 gull y "J i A it y i fa; iii

CATALYTIC CONVERTER This invention relates to the treatment ofautomotive exhaust gases from an internal combustion engine, and moreparticularly, to a catalytic converter for the conversion of the noxiousconstituents of exhaust gases of an internal combustion engine to aharmless form.

The desirability of treating exhaust gases of an internal combustionengine to convert the noxious constituents thereof, particularly carbonmonoxide, unburned hydrocarbons and oxides of nitrogen to a harmlessform is now well established. f the various methods suggested fortreating automotive exhaust gases, one of the most promising is the useof a catalytic converter. in automotive applications a catalyticconverter having a catalytic element positioned therein is placed in theengine exhaust stream whereby exhaust gases from the engine pass intothe converter and through the catalytic element which contains acatalytic material effective to oxidize CO and the unburned hydrocarbonsto CO, and water and/or reduce the oxides or nitrogen to elementaloxygen and nitrogen before being released to the atmosphere.

There are numerous requirements to be met in providing a practical andeffective catalytic converter. First, in converters employing a catalystmaterial in the form of spheres or pellets, it is necessary that thecatalyst bed be kept tightly packed during operation to preventattrition of the catalyst arising from both road vibration andfluidization of the catalyst bed by the exhaust gases flowing throughthe bed. Secondly, it is desirable that the flow of gases through theconverter be uniform for maximum catalyst life and optimum conversion.Thirdly, back pressure in the exhaust stream caused by the restrictionof flow of exhaust gases through the converter must be minimized inorder to achieve proper engine operation. Fourthly, the converter mustbe so designed to prevent differential temperatures throughout theconverter which lead to localized cracking and failure of the converterstructure. Fifthly, the converter must be designed for easy placement inan automobile and for easy access for periodic removal and replacementof the catalyst element.

Accordingly, it is the principal object of this invention to provide animproved catalytic converter suitable for treatment of exhaust gasesmeeting the aforementioned requirements.

It is another object of our invention to provide a catalytic converterhaving inner and outer cylindrical members whereby exhaust gasesentering the converter are dispersed annularly between the members so asto flow uniformly downwardly through a flat, cylindrical elementcontaining tightly packed catalyst spheres effective to convert theexhaust gas to a harmless form whereby the uniform downward flow througha relatively shallow catalyst bed acts to keep the spheres tightlypacked and results in a minimum back pressure in the exhaust stream withmaximum catalyst life and optimum conversion.

In the preferred embodiment of our invention, these and other objectsare accomplished by providing a catalytic converter having an outercylindrical housing and an inner cylindrical element adapted to receivein spaced relationship thereto a flat, cylindrical catalyst elementwhich housing and inner element define an annular manifold therebetweencommunicating with an inlet conduit for feeding exhaust gases into themanifold, the inner element and the catalyst element defining an innermanifold above the catalyst element communicating with the annularmanifold through a plurality of holes in the inner element, wherebyexhaust gases entering the converter are distributed around the annularmanifold and, flow upwardly into the inner manifold and then unifonnlydownwardly through the catalyst bed wherein the conversion reactionstake place to be collected in an outlet manifold surrounding thecatalyst element and discharged from the converter through an outletconduit communicating with the outlet manifold.

These and other objects and advantages will become apparent from thefollowing detailed description of the invention, reference being had tothe accompanying drawings of which:

FIG. 1 is a cross-sectional view of a catalytic converter, and

seen

FIG. 2 is a sectional elevational view of same.

Referring now to the drawings, the catalytic converter shown in FIGS. land 2 comprises, generally, a housing 10 formed preferably of astainless steel or coated or plated steel effective to resist thecorrosive attack of high-temperature gases and salts. The converterhousing it) comprises an outer cylindrical portion 112, an inlet conduit14 for feeding exhaust gases into the converter and an outlet conduit R6for discharging the treated gases from the converter extending radiallyfrom the cylindrical portion l2 and positioned 180 apart. it will benoted that the displacement angle between the conduits may be varieddepending on the placement of the converter in the exhaust system.Conduit supports 18a and 18b attached to the cylindrical portion 112 areprovided to support the conduits l4 and 16, respectively, in thehousing. A top cover 20 is provided above the cylindrical portion 112 ofthe housing having a layer of insulation 22, for example a mineral wool,between the inner and outer top cover walls 24 and 26, respectively, anda removable bottom cover 28 is provided for access to the interior ofthe housing If). A ring clamp 30 secures the bottom cover 28 against thecylindrical portion l2 and an annular seal 32 therebetween prevents gasleakage from the converter.

Within the housing is an inner element 34 including a cylindricalportion 35 in spaced relation to the outer cylindrical portion 12, aradially extending portion 36 attached at one end to the lower portionof the cylindrical housing portion 112 and integrally attached at theother end to the inner cylindrical portion 35, conical baffle portion 38which has a plurality of holes 40 thcrethrough attached to the innerwall 24 of the top cover 20 and a horizontally disposed flange portion42 integrally connecting the baffle 38 to the cylindrical portion 35.The inner element 34 is adapted to receive a removable catalyst element44 against the flanged portion 42 in spaced relationship to thecylindrical portion 35 thereby defining an annular space 45therebetween.

The catalyst element 44 is a flat, cylindrical element having top andbottom plates 46 and 48, respectively, and a nonporous cylindrical rim50 with each of said element plates 46 and 48 having a plurality ofregularly spaced l/l6-inch perforations or louvers 52a and 52b,respectively, therethrough. Prior to assembly the catalyst element 44 isfilled and tightly packed with a desired catalyst 54. The catalyst canbe used in any form, but is preferably in a pelletedl, extruded orspherical form with or without a support or carrier. Preferably, thecatalyst is distributed on or impregnated in a support or carrier whichmay or may not contribute to the catalytic activity of the composite.Our invention is not limited to the use of any particular catalyst butincludes the use of any suitable oxidation or reduction catalyst orcatalyst capable of both oxidation and reduction which is effective atoperating temperatures up to about 1600 F. over extended periods oftime. It is desirable that the catalyst bed be relatively shallow tominimize back pressure in the exhaust system. For example, we have foundthat a bed of about 3-inch depth for an element having a diameter ofabout 12 inches performs adequately.

With the catalyst element 44 in place in the housing 10 there is definedan inlet manifold 56 having an outer annular portion 58 between theouter cylindrical portion 112 of the housing and the inner element 34and an inner portion 60 between the top cover 20 of the housing, the topperforated plate 46 of the catalyst element 44 and the baffle portion38. A bolt 62 with washers 64 located substantially centrally of thehousing 10 and extending between the covers 20 and 22 substantiallycentrally through the element 44 holds the catalyst element 44 tightlyagainst a flange seal 66 in sealing engagement with the flange portion42 of the inner element 34. An outlet manifold 68 is defined between thebottom cover 28 and the inner element 34 extending to the flange seal 66which seals the outlet manifold 68 from the inner manifold portion 60.The outlet manifold 68 includes the aforesaid annular space 45 extendingaround the catalyst element 44 between the cylindrical portion 34 and.the nonporous rim 50 of the catalyst element whereby the catalystelement is, in effeet, immersed or surrounded by the gases in the outletmanifold. The inlet conduit 14 communicates in fluid flow relationshipwith the outer annular portion 58 of the inlet manifold 56, and theoutlet conduit 16 communicates in flow relationship with the outletmanifold 68 through an opening 70 in the annular portion 36 of the innerelement 34 and is sealed from the annular manifold 58 by a sealing plate72 surrounding the entrance thereto.

In operation, gases from an internal combustion engine are carried bythe exhaust manifold (not shown) into the inlet conduit 14 and into theouter annular portion 58 of the inlet 56. The entering gases flowthroughout the annular manifold in an annular path within the housing10. As the gases flow around the annular manifold, they are forcedupwardly and through the holes 40 in the baffle 38 and into the innerinlet manifold portion 60. It may be seen that the gases flow into theinner manifold 60 from substantially all radial directions and arethereby evenly distributed above the catalyst element 44. It may befurther seen that the inwardly sloping configuration of the top cover 20in relation to the horizontally disposed top plate 46 of the element 44serves to maintain a uniform gas pressure across in the inner manifoldportion 60. The gases then flow downwardly through the perforations 52ain the top plate 46 of the element 44 and pass through the catalyst bed54 wherein the oxidation and/or reduction reactions take place. Thetreated gases then flow out through the perforations 52b in the bottomplate 48 of the catalyst element and are collected in the outletmanifold 68. The treated gases then flow into the outlet conduit 16through the opening 70 in the inner element 34 and are discharged downthe tailpipe to the atmosphere.

The catalytic reaction taking place in the catalyst bed is an exothermicreaction and, therefore, the temperature of the bed and of the treatedgas rises from the heat of the reaction. As a result of the heated gasesin the outlet manifold 68 circulating around the catalyst element 44 inspace 45, the temperature of the bed is maintained and the temperaturearound the converter housing is equalized thereby preventingdifferential thermal stresses in the converter structure.

Catalysts typically used in exhaust gas converters usually do not becomeeffective until the temperature of the catalyst has risen to about 250F. As a result, there is a time lapse between the emission of exhaustgas from the engine on startup to when catalytic conversion of the gasesbegins through heating of the catalyst bed by the incoming exhaustgases. As previously stated, the catalytic reaction is an exothermicreaction and, therefore, the treated gases are heated to a temperaturehigher than the incoming gases in the converter structure. As may beseen, in our converter the catalyst element 44 is immersed in thetreated exhaust gases in the outlet manifold 68 whereby the bedtemperature is maintained. Furthermore, the incoming gases are heated bythe treated gases through the portion of the inner member 34 which formsa common wall between the outlet manifold 68 including space 45 and theannular portion 58 of the inlet manifold 56. In this manner, on startupthe incoming gases are quickly heated by the treated gases therebydecreasing the time before the catalyst bed reaches startup temperatureand thereby increasing the efficiency of the converter.

Although our invention has been described in terms of a specificembodiment, it is to be understood that other forms may be adaptedwithin the scope of the invention.

We claim:

1. An exhaust gas catalytic converter comprising, in combination, ahousing comprising a cylindrical portion, radially extending inlet andoutlet conduits, a top cover portion and a bottom cover portion, saidcylindrical portion being adapted to receive a flat, cylindricalcatalyst element having perforated top and bottom plates and having ahorizontally disposed catalyst bed therebetween, means adapted toprovide a seal between said catalyst element and said cylindricalportion, an annular baffle within said housing extending between saidcylindrical portion and said top cover portion defining with sa|delement an inlet manifold having an outer annular portion communicatingwith said inlet conduit and an inner portion, said seal means, saidcylindrical portion, said element and said bottom cover portion definingan outlet manifold communicating with said outlet conduit, said outerannular portion communicating with said inner portion through aplurality of holes in said baffle whereby exhaust gases entering saidouter annular portion are evenly distributed into said inner portionthrough said holes and whereby the flow of exhaust gases from said innerportion downwardly through said bed and into said outlet manifold issubstantially uniform.

2. An exhaust gas catalytic converter comprising, in combination, ahousing comprising a cylindrical portion, radially extending inlet andoutlet conduits, a top cover portion and a bottom cover portion, a flat,cylindrical catalyst element hav ing perforated top and bottom platesand having a horizontally disposed catalyst bed therebetween mounted insaid housing, means adapted to provide a seal between said catalystelement and said cylindrical portion, an annular baffle within saidhousing extending between said cylindrical portion and said top coverportion defining with said element an inlet manifold having an outerannular portion communicating with said inlet conduit and an innerportion, said seal means, said cylindrical portion, said element andsaid bottom cover portion defining an outlet manifold communicating withsaid outlet conduit, said outer annular portion communicating with saidinner portion through a plurality of holes in said baffle wherebyexhaust gases entering said outer annular portion are evenly distributedinto said inner portion through said holes and whereby the flow ofexhaust gases from said portion downwardly through said bed and intosaid outlet manifold is substantially uniform.

3. A catalytic converter for treatment of exhaust gases of an internalcombustion engine to remove the noxious constituents thereof comprising,in combination, an outer housing comprising a cylindrical portion, aradially extending inlet conduit for feeding exhaust gases into saidconverter, a radially extending outlet conduit for discharging thetreated exhaust gases from said converter, a top cover portion and abottom cover portion, an inner element comprising a cylindrical portionattached to said cylindrical portion of said outer housing through aradially extending portion of said element, a conical baffle portionattached to said top cover portion, and a horizontally disposed flangeportion connecting saidbaffle portion to said cylindrical portion ofsaid element, said baffle portion having a plurality of holestherethrough, said inner element being adapted to receive in spacedrelationship to said cylindrical portion thereof a flat, cylindricalcatalyst element having perforated top and bottom plates and ahorizontally disposed catalyst bed therebetween, annular sealing meansadapted to provide a seal between said catalyst element and said innerelement at said horizontal flange portion and fastening means locatedsubstantially centrally of said housing extending between said coverssubstantially centrally of said element adapted to tightly engage saidelement against said seal, said cylindrical portion of said elementbeing spaced apart from said cylindrical portion of said therebydefining an annular manifold communicating with said inlet conduit, saidtop plate of said element being spaced apart from said top cover portionof said housing thereby defining an inner manifold interiorly of saidconical baffle portion, and said inner element and said catalyst elementbeing spaced apart from said bottom cover portion, thereby defining anoutlet manifold extending to said sealing means and communicating withsaid outlet conduit, said annular manifold communicating with said innermanifold through said holes in said baffle whereby exhaust gasesentering said annular manifold are evenly distributed across saidelement top plate in said inner manifold whereby the flow of exhaustgases from said inner manifold downwardly through said catalyst bed andinto said outlet manifold is substantially uniform.

l0l007 (H68 2 3 5 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 3,515,255 Dated October 26, 1971 InvencorQ's) It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

" Column 2, line 29, after "portion 35, insert an inwardly slanting orColumn 3, line 11, after "inlet" insert manifold Claim 2, line 31,between "said" and "portion" insert inner Claim 3, line 58, between saidand "thereby" insert housing Signed and sealed this 9th day of May 1972.

(SEAL) A c, be st:

EDWARD MHFLE'TCHER JR. ROBERT GOTTSCHALK Ahbesting Officer Commissionerof Patents

2. An exhaust gas catalytic converter comprising, in combination, ahousing comprising a cylindrical portion, radially extending inlet andoutlet conduits, a top cover portion and a bottom cover portion, a flat,cylindrical catalyst element having perforated top and bottom plates andhaving a horizontally disposed catalyst bed therebetween mounted in saidhousing, means adapted to provide a seal between said catalyst elementand said cylindrical portion, an annular baffle within said housingextending between said cylindrical portion and said top cover portiondefining with said element an inlet manifold having an outer annularportion communicating with said inlet conduit and an inner portion, saidseal means, said cylindrical portion, said element and said bottom coverportion defining an outlet manifold communicating with said outletconduit, said outer annular portion communicating with said innerportion through a plurality of holes in said baffle whereby exhaustgases entering said outer annular portion are evenly distributed intosaid inner portion through said holes and wherebY the flow of exhaustgases from said portion downwardly through said bed and into said outletmanifold is substantially uniform.
 3. A catalytic converter fortreatment of exhaust gases of an internal combustion engine to removethe noxious constituents thereof comprising, in combination, an outerhousing comprising a cylindrical portion, a radially extending inletconduit for feeding exhaust gases into said converter, a radiallyextending outlet conduit for discharging the treated exhaust gases fromsaid converter, a top cover portion and a bottom cover portion, an innerelement comprising a cylindrical portion attached to said cylindricalportion of said outer housing through a radially extending portion ofsaid element, a conical baffle portion attached to said top coverportion, and a horizontally disposed flange portion connecting saidbaffle portion to said cylindrical portion of said element, said baffleportion having a plurality of holes therethrough, said inner elementbeing adapted to receive in spaced relationship to said cylindricalportion thereof a flat, cylindrical catalyst element having perforatedtop and bottom plates and a horizontally disposed catalyst bedtherebetween, annular sealing means adapted to provide a seal betweensaid catalyst element and said inner element at said horizontal flangeportion and fastening means located substantially centrally of saidhousing extending between said covers substantially centrally of saidelement adapted to tightly engage said element against said seal, saidcylindrical portion of said element being spaced apart from saidcylindrical portion of said thereby defining an annular manifoldcommunicating with said inlet conduit, said top plate of said elementbeing spaced apart from said top cover portion of said housing therebydefining an inner manifold interiorly of said conical baffle portion,and said inner element and said catalyst element being spaced apart fromsaid bottom cover portion, thereby defining an outlet manifold extendingto said sealing means and communicating with said outlet conduit, saidannular manifold communicating with said inner manifold through saidholes in said baffle whereby exhaust gases entering said annularmanifold are evenly distributed across said element top plate in saidinner manifold whereby the flow of exhaust gases from said innermanifold downwardly through said catalyst bed and into said outletmanifold is substantially uniform.